Swage fasteners can be of a pull type or stump type. A typical swage type fastener includes a pin and a collar with the pull type fastener having a pin shank having a locking portion with lock grooves and a pull portion with pull grooves. The pull grooves are adapted to be gripped by matching teeth in chuck jaws of an installation tool having a swage anvil adapted to engage the collar whereby a relative axial force can be applied between the pin and collar to move the anvil over the collar to swage it into the lock grooves.
With respect to swage fasteners of the pull type, the pull portion is connected to the lock groove portion via a breakneck groove of reduced strength which is adapted to fracture at a preselected magnitude of axial tensile force greater than required to swage the collar whereby the pull portion, or pintail, will be severed and removed from the pin shank after completion of swaging. The breakneck groove is of sufficient strength to withstand the high tensile load for swaging and the pull grooves must be similarly of sufficient strength to accept the relative axial pull load applied by the engaged teeth of chuck jaws of the installation tool. This routinely requires that the pull portion be of a relatively large diameter so as to have sufficient material to provide the necessary size and strength for the breakneck groove and also to inhibit fracturing of the pull grooves instead of the breakneck groove.
A typical stump type fastener includes a pin and a collar that has a pin shank having a locking portion with lock grooves. The difference between a swage fastener of the pull type and the stump type is that the stump type does not have a pull portion with pull grooves. Also, in the stump type fastener system, an installation tool is used that has a swage anvil adapted to engage the collar to apply a relative axial force between the pin and collar to move the anvil over the collar to swage it into the lock grooves and a bucking member that is used to engage the pin head.
U.S. Pat. Nos. 6,325,582, 6,233,802, 5,125,778, 5,090,852, 5,049,016, 4,867,625, 4,813,834, 4,472,096, 4,221,152 and 4,208,943 were issued to the assignee of the present invention or a predecessor in interest. These patents all relate to various swage fastener designs and are representative of the art. In the prior art, a fastener was typically optimized for a particular collar for a particular application. Also, in the prior art, fasteners typically had a single grip range. A single grip range means that a fastener could fasten workpieces that have variations in thickness of 1/16 of an inch.
The optimization technique employed by the present invention departs from the prior art practice of optimizing a fastener for a particular collar for a particular application. In the present invention, the lock groove and crest geometry is optimized for use in a plurality of applications wherein the lock grooves and crests are each provided with the longest width required for a specific application to provide the fastening system with satisfactory clamp and tensile loads and resistance to failure in the plurality of applications when the lock grooves are filled with various materials from different collars of various strengths. Also, the lock groove and crest geometry is of a uniform construction that is used in the plurality of applications that enables the lock grooves and crests for each pin diameter to be manufactured with tooling that uses a common lock groove and crest geometry. Such an approach reduces costs associated with the tooling.
Additionally, for each pin size, certain collars of different materials have about the same outside diameter so an installation tool with a uniform swage anvil geometry can be used to swage those collars of different materials into the lock grooves to install the swage type fastener in workpieces for shear, shear/tension, shear composite and shear/tension composite application. Such an approach reduces the costs associated with labor in exchanging a swage anvil in the tool that is used in such applications.
Furthermore, the fastener of the present invention has a double grip range. Double grip means that a fastener can fasten workpieces that vary in thickness up to ⅛ of an inch. Such an approach increases the versatility of the fastener.